fix prompts

app.py

@@ -239,6 +239,10 @@ def inference(img, text, is_translation, prompt=None):
     model = model.eval() 
     device = CUDA(0) if is_gpu else "cpu"
     model = model.to(device)
+
+    promt = prompt.strip()
+    if not prompt:
+        prompt = None
     if is_translation:
         # encode text
         if text is None:
@@ -277,7 +281,7 @@ inputs = [
     gr.inputs.Image(type="file", label="Image to generate Vietnamese caption", optional=True),
     gr.inputs.Textbox(lines=2, placeholder="English sentence for translation"),
     gr.inputs.Checkbox(),
-    gr.inputs.Textbox(lines=1, placeholder="Prompt [Optional]", optional=True)
+    gr.inputs.Textbox(lines=1, placeholder="Prompt [Optional]")
 ]
 
 gr.Interface(